The objective of the present study was to assess the effect of the aqueous root extract of Cryptolepis
sanguinolenta (cryptolepis), a popular West Africa antimalarial agent on ovulation in rabbits. We demonstrated
previously that the aqueous root extract of the plant inhibits reproduction and foetal development in mice. The
possible mechanism involved in this reproductive effect and whether the effect is species dependent has yet to be
elucidated. Using the rabbit, the present study examined the effect of cryptolepis on pre and post ovulatory events to
explore further the mechanism of the reproductive toxicity of cryptolepis. Cryptolepis (62.5-500 mg/kg; p.o)
administered five hours before ovulation inhibited ovulation in rabbits as ovarian histology showed dilated but
unraptured ovum. The effects of cryptolepis were similar to diclofenac, an NSAID used as a reference drug. Post
ovulatory treatment with cryptolepis (62.5-500 mg/kg; p.o) had little effect on ovarian histology but decreased the
implantation index. This study shows that the anti-conceptive effects of cryptolepis involve inhibition of ovulation
and early post ovulatory events in the rabbit.